Question regarding BMW E46 exhaust. Help

[pringle1988]

Hello all

After taking off my exhaust off at the weekend to work on the prop shaft I noticed there are 2 rubber cylindrical attachments connected to the back box and center silencer. They have 60Hz written on them and are held on by a single bolt.
Can anybody help me and identify what these are?

Many Thanks.

[pringle1988]

Sorry for the shameless bump, just would like to know before it goes back onto the car.

Thanks again.

[300bhp/ton]

They must be some kind of harmonic dampener I'd have thought.